<template>
  <div>
    孙组件{{ a }}
    <button @click="incrementA">为父组件a+6</button>
  </div>
</template>

<script lang="ts" setup>
const props = defineProps(['b', 'a', 'addA'])
function incrementA() {
  props.addA(6)
}
</script>

<style lang="scss" scoped></style>
